We propose a series of investigations to test the feasibility of frequency domain photon migration (FDPM) as a method for noninvasive determination of the integrity of silicone (polydimethylsiloxane, PDMS) filled breast implants and the physiologic changes related to these implants. The existing FDPM apparatus currently employed at the Laser Microbeam and Medical Program (LAMMP) for noninvasive studies of breast lesions will be with the addition of a laser diode matched to the absorption band if silicone. Experiments will involve collection of FDPM data from tissue phantoms containing scatterer and absorber in addition to silicone in order to establish accuracy and sensitivity of the method to silicone detection and quantification. Silicone concentrations will be calculated using both classical least squares and partial least squares (PLS) methods. After characterization of silicone specific FDPM in vitro, experimentation on patients scheduled for explant surgery can b e performed. This technology, if shown to be feasible, would provide a noninvasive tool that could be used to assist in enumeration of the health risks associated with silicone filled implants.